Thanks for pointing me in the right direction. The rectifier CR5 seems fine, I should replace it but I can't find a supplier in Australia for them. Although it is listed on the schematics as a GI854, the actual diode on my board is a GI824. The soldier points around Q3 (labeled Q2 on my board) seemed tarnished so I removed Q2 ( BU406 ) and it seems to test faulty. As for the second Mac Plus: I can see arcing on the Flyback Transformer ( I guess it is shot!).

...to be continued